The dyadic system or dual system is the place value system with the base 2, i.e. it provides the dyadic (2-adic) representation of numbers (dyadic) (Greek δύο = two). In the binary system, there are only the digits 0 and 1, which always alternate in the last position and the sequence of digits is extended with each number after 1.
For example, 0 = 0, 1 = 1, the next higher number is 0 again at the end - so 2 in the decimal system is 10 in the binary system, 3 in the decimal system is 1 again in the dual system, i.e. 3 = 11 and for 4 one more position and 0 again at the end, i.e. 4 = 100, etc. The sequence of digits is extended with each number, with 0 and 1 always alternating at the end.
Due to its importance in digital technology, the dyadic system is the most important number system alongside the decimal system. In medicine, for example, a dyadic system refers to the classification of vascular malformations under molecular genetic aspects, to which clinical entities are assigned.